Synthesis of Nanocomposites Layered Double Hydroxide via Ocimum basilicum and Its Acaricidal Efficacy Against Multi-Resistance Rhipicephalus annulatus Tick.

Abstract

A layered double hydroxide (LDH) incorporated with Ocimum basilicum essential oil (OB) was prepared and its acaricide efficacy against Rhipicephalus annulatus tick was investigated. The OB essential oil was extracted from plants farmed in the study area. Zn-Al LDH/Gallate was prepared by co-precipitation method then OB oil was added to obtain OB/LDH nano-composite. The obtained product was characterized by X-Ray Diffraction (XRD), Fourier-transform infrared (FT-IR) and scanning electron microscopy (SEM). The acaricidal activity of different concentrations of the obtained OB/LDH nanocomposite (6.25, 12.5, 25, 50, 100, 200 and 300 l/mL) was evaluated via the adult immersion test (AIT), egg hatchability test (EHT), larval packet test (LPT) and repellency test. OB oil and OB/LDH nano-composite showed 100% adult mortality and prevent egg deposition at a dose of 300 l/mL. Also, eggs hatching was fully inhibited at 300 l/mL while at the concentration of 200 l/mL the inhibition rate was 95%. In LPT, OB/LDH showed a high toxicological effect which leading to 100% and 43% larval mortality at doses of 200 μ l/mL and 100 μl/mL, respectively. Meanwhile OB alone showed 100% and 45% larval mortality at doses of 300 μl/mL and 200 μl/mL, respectively. The LC50, LC90 and LC99 values of OB/LDH and OB were found to be 107.46 versus 209.908 μl/mL, 171.22 versus 282.63 μl/mL and 196.15 versus 298.26 μl/mL, respectively. The repellence activity was lasted for 3 h after application against larvae. OB/LDH was found to be more repellent than OB as evidenced by the RC50 values after 2 h and 3 h (48.82 vs. 79.99 μl/mL and 89.47 vs. 185.32μ l/mL, respectively). Overall, our results proved that LDH enhanced the larvaicidal and repellent efficacy of OB against R. annulatus tick larvae.